1. Field of the Invention
The present invention relates generally to the field of input/output cards for data processing systems. More particularly, the present invention relates to the field of circuitry configurations within input/output cards.
2. Description of the Related Art
Data processing systems have been configured for use with peripheral or input/output (I/O) cards that provide increased functionality for the data processing system. As one example, I/O cards may be used to provide for increased memory capacity for the data processing system. I/O cards may also be used to provide for communications capabilities for the data processing system over a telephone line, for example, with external hosts, data processing systems, or networks for example. I/O cards typically contain a single printed circuit board having electronics and circuitry to implement their functionality.
I/O cards are typically portable cards that may be inserted into and detached from a socket housed within the data processing system. The data processing system and I/O cards may be configured such that different types of I/O cards, such as a modem card or a memory card for example, may be interchangeably inserted in, used, and removed from the same socket. I/O cards provide convenience for users in allowing them to install, as desired, additional capabilities for the data processing system.
The Personal Computer Memory Card International Association (PCMCIA) has devised standards for I/O cards to provide compatibility between various data processing systems and various I/O cards. The PCMCIA standards specify, for example, a 68-pin connector at one end of a PCMCIA card for insertion into a compatible socket in the data processing system. The 68-pin connector provides for a communication interface between the data processing system and the PCMCIA card. To provide communication capabilities for the data processing system, PCMCIA cards may also be configured with another connector for communication over an external network with other data processing systems, for example. This other connector is typically located at the end of the PCMCIA card opposite the 68-pin connector.
The PCMCIA standards also specify the storage of a printed circuit board within a package having specified dimensions for the I/O card. PCMCIA cards may have a Type I, Type II, or Type III packaging format. All three packaging formats specify external dimensions of approximately 85.6 millimeters in length by approximately 54.0 millimeters in width. Type I PCMCIA card is approximately 3.3 millimeters thick. Type II PCMCIA card is approximately 5.0 millimeters thick. Type III PCMCIA card is approximately 10.5 millimeters thick. The functionality provided by PCMCIA cards, however, may be limited as only a limited amount of electronics and circuitry may be configured on a single printed circuit board within the external dimensions specified for each type of PCMCIA card.